Liquid crystal display (LCD) technology driven by an active array uses a dual-polarization characteristic to control an arrangement direction of liquid crystal molecules by applying an electric field, so as to carry out a switching control for an optical path travel direction of a backlight source. According to different electric field applying directions to the liquid crystal molecules, the LCD display mode is divided into a TN (Twist Nematic) series mode, a VA (Vertical Alignment) series mode, and an IPS (In-Plane Switching) series mode. The VA series mode is to apply a longitudinal electric field to the liquid crystal molecules, and the IPS series mode is to apply a transverse electric field to the liquid crystal molecules. In the IPS series mode, according to different applying transverse electric fields, it is further divided into an IPS mode and an FFS mode, etc. Each of the pixel units of the FFS display mode has an upper layer electrode and a lower layer electrode, namely a pixel electrode and a common electrode, and the lower layer common electrode is laid with an entire surface method in an aperture region. The FFS display mode has the advantages of: high penetration ratio, large viewing angle, and lower color shift, so that it has become a widely applied LCD display technology.
For improving the stability of an oxide TFT (thin film transistor), an etch stop layer (ESL) structure has been widely adopted, and the structure can efficaciously decrease influences for back channels from external environment factors and etching damage of source and drain electrodes. However, a manufacturing method of a traditional FFS display mode with the ESL structure requires an increased number of masks, so that the process complexity and the manufacturing cost are increased.